This doesn't answer your question, but it does give some context and other examples. I have a Mirage G4 M4 with an Optimum 176 in it. Reserve fits great (and deploys out of there great btw).  Canopies I have had in this rig and MY impression of how they fit. 
  Demo'ed a Storm 190. Super tight. Would not do it again. 
 Sabre2 170. Fits like a glove. Perfect.  Own and jump this canopy.  
 Demo'ed a Pulse 190. Fit great. Might be something for you to think about. Not the sporty-ist canopy, but actually liked it and think it is a good canopy at a reasonable wing loading. The bottom skin makes this super easy to pack and very low volume.
 Spectre 170. Fits great. I own and use this canopy for wing suiting. 
 Demo'ed a Pilot 168 ZP. Canopy was brand new and was really tight but ok in my container. I don't have any doubt that after it was broken in with some jumps it would fit better/fine.  Definitely packed larger than my Sabre2. 
  I have found some of Mirage's suggestions on canopies to not quite fit with my expectations and experience (i.e. a 190 Storm, for example).  I load my 170's about 1.3 or so. 
  I don't have first hand experience with ZPX but was leaning towards a Pilot for a while and did a bunch of reading and asking figment questions and never got very good answers I felt comfortable with, as it seems you are now experiencing. Good luck with the process, I know it can be frustrating.